Method and Device for Subsea Wire Line Drilling

ABSTRACT

A method and a device for subsea wire line drilling permit the recovery of a full core barrel with a coiled tubing, without pulling up a drill string.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method and a device for subsea wire line drilling. The invention is intended to be used with a subsea drilling system, such as that described in co-pending U.S. Patent Application No. (Attorney Docket No. F-8973), filed on the same date as the instant application and the disclosure of which is hereby incorporated into the instant application in its entirety.

2. Description of Related Art

Prior art wire line subsea drilling devices have not used coiled tubing and have required a drill string to be pulled up in order to recover cores.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a method and a device for subsea wire line drilling, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and in which wire line core retrieval is accomplished by using coiled tubing and cores can be recovered without pulling up the drill string.

With the foregoing and other objects in view there is provided, in accordance with the invention, a method subsea for wire line drilling. The method comprises drilling a hole in a seafloor with a drill string, running coiled tubing down the drill string to a full core barrel having a core and latching the coiled tubing onto the full core barrel, recovering the full core barrel with the coiled tubing without pulling up the drill string, inserting the full core barrel into a tool carousel, retrieving an empty core barrel from the tool carousel, attaching the coiled tubing to the empty core barrel, lowering the empty core barrel into the drill string, unlatching the coiled tubing from the empty core barrel, and restarting drilling to recover another core.

With the objects of the invention in view, there is concomitantly provided a

device for subsea wire line drilling. The device comprises a drilling head to be disposed under water, and a wire line coiled tubing system associated with the drilling head underwater. The coiled tubing system includes a reel, coiled tubing wound on the reel, a drill string with a drill rod and a drill bit, and a core barrel to be latched to the coiled tubing for recovering cores without pulling up the drill string.

Drilling processes with a drilling system that uses only a wire rope to retrieve and deploy core barrels have only been employed in the past for land drilling. The invention uses such a process for the first time for underwater drilling with a coiled tubing reel.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a method and a device for subsea wire line drilling, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a longitudinal-sectional view of a coiled subsea tubing system;

FIG. 2 is a reduced, perspective view of the coiled subsea tubing system with the drilling head moveable thereon;

FIG. 3 is an elevational view of the coiled subsea tubing system with a core barrel which has been retrieved;

FIG. 4 is an elevational view of the coiled subsea tubing system illustrating a sequence of disconnecting a coiled tubing reel from the core barrel;

FIG. 5 is an elevational view of the coiled subsea tubing system illustrating a process step in which an empty core barrel is to be dropped into a drill string; and

FIG. 6 is an elevational view of the coiled subsea tubing system illustrating a sequence step in which the empty core barrel is dropped, latched and ready to drill into the drill string.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a longitudinal-sectional view of a coiled subsea tubing system 1, which is used to retrieve wire line cores from a drilling operation. The coiled tubing system 1 also has the ability to send telemetry, indicated by reference numeral 4, to the surface through a line 5 and subsea drilling system instrumentation 6, using a subsea drilling system described in co-pending U.S. Patent Application No. (Attorney Docket No. F-8973), filed on the same date as the instant application. The coiled tubing system 1 also has a coiled tube reel 8 with a slip ring 9 connected to the line 5, and a tube straightener 11. The coiled tubing 12 is basically steel tubing wound on the reel 8, which requires the straightener 11 before it is used. An injector 14 is used to push and pull the coiled tubing 12 down a hole. The coiled tubing reel 8, the straightener 11 and the injector 14 are located on top of the subsea drilling system.

FIG. 1 also shows a drilling head 2, which is described in more detail in co-pending U.S. Patent Application No. (Attorney Docket No. F-8973), filed on the same date as the instant application. The drilling head 2 has a spindle assembly 3 as well as a non-illustrated hydraulic spindle drive motor and drive belt. The drilling head 2 can move up and down, as is indicated by a doubled-headed arrow 15, and has a water inlet 16 leading into the drilling head. This structure according to the invention permits drilling without pulling the rods up continuously, as in diamond drilling. A drill rod 17, which makes up a drill string 18, has an open/close valve 20 at the top and a drill bit 21 at the bottom. A core barrel 22 is connected to the coiled tubing 12 at a latch 23, below the seafloor 25, and extends into the drill bit 21, as in diamond drilling. The coiled tubing 12 is used to recover cores without pulling the drill string 18 back up.

FIG. 2 is a perspective view of the coiled tubing system 1, in which the instrumentation 6, the slip ring 9, the reel 8, the coiled tubing 12, the straightener 11, the injector 14 and the drilling head 2 can be seen. The figure also shows hydraulic cylinders 27, 28 on which the drilling head 2 moves up and down in the direction of the arrow 15 and receives water at the inlet 16. In addition, there are seen cylinder rods 29, 30 connected at the bottom to a machine frame. FIG. 2 illustrates the coiled tubing system as drilling is started into the hole, and additional drill rods 17 are added. As each core barrel 22 is full, the core is recovered and pulled up by the coil tube reel.

FIG. 3 shows a core barrel 22 with a core 32 which has just been pulled up by the coiled tubing reel 8 in the direction of an arrow 33 and retrieved from the drill rod 17 of the drill string 18. It may also be seen that the drill with the bit 21 stays in the hole during drilling, but the core can be pulled from the drill string 18 and also replaced by using the coiled tubing system 1. Upper and lower tool arms 35, 39 with respective grippers 35′, 39′ and a tool carousel 36, as described in more detail in co-pending U.S. Patent Application No. (Attorney Docket No. F-8973), filed on the same date as the instant application, with drilling tools 37, 38 and core barrels 22, can be seen on the left in FIG. 3. The upper tool arm 35, which is a grabber tool arm, and the lower tool arm 39, which is an alignment tool arm, are used to grab the core, align it and replace it, that is, to grab the core, disconnect it from the coiled tubing reel and place it back into the tool carousel 36.

FIG. 4 shows a step in a sequence of operation of the coiled tubing system 1, in which the coiled tubing reel 8 is disconnected from the core barrel 22 and the tool arms 35, 39 are used to deploy and store the core 32 in the carousel 36. The tool arms 35, 39 are also used to retrieve an empty core barrel 22, which can be put down to the drill string 18 later on.

FIG. 5 shows a process step in which the coiled tubing reel 8 is connected to an empty core barrel 22 that is ready to drop into the drill string 18 in the direction of an arrow 40, at a connection location 42. It may be seen that an outer barrel housing 44 of the core barrel 22, the drill string 18 and the drill bit 21, are deployed in this process step.

FIG. 6 shows a step in the sequence of operation of the coiled tubing system 1, in which the empty core barrel 22 has been dropped down, latched and is ready to drill into the drill string 18. The figure shows the coiled tubing 12 disconnected from the core barrel 22 and ready to recover the core barrel when it becomes full again. This drilling process according to the invention does not require the drill rods 17 to be recovered every time there is a core 32 to be recovered and therefore is a faster drilling process than in the prior art. Processes have only been used in the past with a land drilling system that is merely a wire rope for retrieving and deploying core barrels. Such a process has never been used for underwater drilling with a coiled tubing reel.

In summary, the sequence of operation of the coiled tubing system 1 is to drill a hole, run the coiled tubing 12 down to a core barrel 22 and latch on to it. Then the core barrel 22 is recovered using the coiled tubing reel 8 itself. Once the core barrel 22 is recovered, the arms 35, 39 are used to deploy the full core barrel 22 to the tool carousel 36 and again to retrieve an empty core barrel 22. The next step is then to attach the coiled tubing 12 to the empty core barrel 22, place it into the drill string 18 using the tool arms 35, 39, then lower it down the drill string 18 until it latches into the outer barrel housing 44 of the core barrel 22. Then the coiled tubing 12 is unlatched from the core barrel 22 and drilling can be started again to recover another core 32. 

1. A method for subsea wire line drilling, the method comprising the following steps: drilling a hole in a seafloor with a drill string; running coiled tubing down the drill string to a full core barrel having a core and latching the coiled tubing onto the full core barrel; recovering the full core barrel with the coiled tubing without pulling up the drill string; inserting the full core barrel into a tool carousel; retrieving an empty core barrel from the tool carousel; attaching the coiled tubing to the empty core barrel; lowering the empty core barrel into the drill string; unlatching the coiled tubing from the empty core barrel; and restarting drilling to recover another core.
 2. A device for subsea wire line drilling, the device comprising: a drilling head to be disposed under water; and a wire line coiled tubing system associated with said drilling head under water, said coiled tubing system including a reel, coiled tubing wound on said reel, a drill string with a drill rod and a drill bit, and a core barrel to be latched to said coiled tubing for recovering cores without pulling up said drill string.
 3. The device according to claim 2, which further comprises instrumentation associated with said reel for sending telemetry to the surface.
 4. The device according to claim 2, which further comprises a tube straightener downstream of said reel in tube travel direction into a hole, and an injector downstream of said tube straightener for injecting said coiled tubing into the hole.
 5. The device according to claim 2, which further comprises a tool carousel, and tool arms for inserting said core barrel into and removing said core barrel from said tool carousel. 